This invention relates to an improved system or apparatus for the analysis of elevator traffic demand.
For the more efficient operation of a plurality of elevator cars, a tendency exists towards resorting to group control in which a most appropriate elevator car in a plurality of elevator cars is selected as a function of changing traffic demands and in response to the occurrence of a floor call.
However, it may frequently happen that the car most appropriate at the time of a floor call occurrence turns out to be inappropriate due to subsequent changes in traffic demand. Furthermore, in an instantaneous forecast system, i.e. a system in which a car corresponding to a floor call is indicated by an arrival forecast lamp upon activation of a respective floor button, the result of poor selection is immediately apparent since the allocated car, once decided, cannot be easily changed.
On the other hand, transition of traffic demand in a building over e.g. a one-day cycle occurs in a substantially fixed pattern. In this regard, it has been proposed to utilize the information of the traffic demand during predetermined unit time intervals observed in the past, which were recorded and processed statistically, and to perform group control based on the traffic demand thus estimated for future times. In this manner, the efficiency of the group control operation may be improved drastically. In this case, however, problems arose of determining the manner in which to process the past traffic volume data of the same predetermined unit time intervals statistically, and the manner in which to preestimate future traffic demands.
The simplest method of processing the past traffic demand for the same time intervals statistically and to preestimate future traffic demands is to sum up certain traffic volume information; for example, the number of times floor calls occurred during predetermined unit time periods each day, wherein each of said predetermined time periods is divided by the number of calls during that time interval to derived a mean value which is used to postulate that the same number of floor calls respective to each of the mean values will occur in the course of the respective predetermined time period of the next day.
However, with this system, in case of seasonal or other changes in the traffic demand in the building, the traffic demand that prevailed before the changes have occurred is necessarily taken into account in computing the mean value and hence the resulting mean value does not reflect the actual traffic demand. On the other hand, it is not proper to postulate that the traffic demand during predetermined time periods of the preceding day are equal to the traffic demand during the same predetermined time periods of the current day. This is because the data of the preceding day may have been much different than usual due to some peculiar traffic states.